Embodiments of the present invention relate to an energy storage system and method for energy management and control, primarily for use in electrical systems such as vehicle drive systems, specifically a multi-source energy storage system and method for energy management and control.
As problems with pollution have become more serious, electric vehicles and renewable energy sources have become increasingly attractive. Pure electric vehicles are driven by power supplied to the electric motor using stored electrical energy. Pure electric vehicles can use one or more stored electrical energy sources. For example, a first electrical energy storage source, such as battery energy, can be used to provide longer lasting energy, and a second electrical energy storage source, such as a power battery, can be used to supply high powered energy, for use in accelerating, etc. Hybrid electrical vehicles are driven by a combination of an internal-combustion engine and an electric motor powered by an energy storage device (such as a traction battery). This combination runs by ensuring that the internal-combustion engine and the electric motor both operate at their highest efficiencies, increasing the overall fuel efficiency. For example, the efficiency of the electric motor is higher when accelerating from standstill and the efficiency of the internal-combustion engine is higher when the engine is running constantly over a period of time (for example, when driving on highways). Enhancing the initial acceleration of the electric motor allows the internal-combustion engine in hybrid vehicles to be smaller and more fuel-efficient.
If the size of high energy density batteries in pure battery-powered electric vehicles and plug-in hybrid vehicles are reasonable, then a single charge is sufficient to meet mileage requirements. However, due to their relatively low power densities, high energy density batteries of the same size might be unable to satisfy power requirements caused by instant acceleration or uphill driving. This is especially apparent in heavy-duty applications, such as city buses or trucks. In view of this, multiple energy sources or hybrid energy sources can be used to simultaneously satisfy mileage requirements and power requirements, without having to excessively increase the size of single high energy density batteries. As power batteries have a higher power density and longer service life, they can be used in combination with high energy density batteries as a hybrid power source in heavy-duty electric vehicles. However, when introducing multiple energy sources or hybrid energy sources into a vehicle's drive system, the allocation and control of these multiple or hybrid energy sources become complicated. The question of how to reasonably allocate and control multiple energy sources or hybrid energy sources to improve the efficient operation of a vehicle's drive systems and cope with a variety of working conditions still needs to be resolved within the industry.
Therefore, a system and method are required to resolve at least one of the problems above.